Three redesigned cars in 12 months isn't a big deal for most car companies. But it is for Porsche.

Porsche has only five model lines and by year end, three of its four cars will have been overhauled. The redesigned Porsche 911 coupe and convertible went on sale Feb. 4. The third-generation Boxster roadster debuts in June and the redesigned Cayman coupe comes at year end.

And more new product is coming. A diesel-powered Cayenne SUV debuted at the New York auto show and goes on sale in September. Over the next two years, Porsche will roll out the 918 Spyder hybrid supercar, the all-new Macan compact SUV and more variants of the 911.

Porsche expects U.S. sales to grow to about 50,000 units in the next five to six years, up from 29,023 in 2011.

The tidal wave of new product and anticipated rise in volume means U.S. dealer profits will grow and they can invest in their dealerships, says Detlev von Platen, CEO of Porsche Cars North America.

The average Porsche dealership has a 3.2 percent return on sales, von Platen says. According to NADA industry analysis data, the average return on sales for U.S. dealers in 2011 was 2.3 percent.

But Porsche isn't developing a new facilities program for its 194 dealers, von Platen says. He and Porsche's top U.S. managers have met with every dealer this year to discuss and set up individual growth and expansion plans. Some will have to expand their showrooms, von Platen says.

Von Platen says Porsche Cars North America is also making substantial investments. It will spend $100 million on a new headquarters with a test track, museum, dealer training center, customer shops and a restaurant in Atlanta and a "Porsche Experience Center" near the Los Angeles airport on 51 acres with even more features.

The diesel-powered Cayenne SUV debuted at the New York auto show and goes on sale in September.